Consumers are increasingly trying to avoid caffeine due to unwanted health effects, including insomnia and irritability. The test could be another tool that eventually leads to a reduction in demand for products containing caffeine.
Chemists at Washington University School of Medicine in St. Louis are developing a quick, "dipstick" test that they say could represent the first home testing kit to detect the common stimulant.
Products do not always indicate whether they contain caffeine, and the caffeine content of similar food products can vary widely depending on the manufacturer. Even drinks that are labeled "decaf" can contain detectable amounts of caffeine, experts say.
"We envisioned that a simple method to measure caffeine, even in hot beverages, such as coffee, would be of value to individuals and institutions wanting to verify the absence of caffeine," said study leader Jack Ladenson, a chemist at the university. "This will greatly assist individuals who wish to avoid caffeine."
Ladenson said he is developing test strips treated with a specific antibody that react by changing colour in the presence of caffeine.
The new test will be designed to be qualitative only, he said. It allows a person to quickly determine whether caffeine is present, but does not indicate the exact amount or concentration of caffeine.
In preliminary tests using coffee and cola, an experimental version of the test effectively distinguished caffeinated versions of these products from their decaf counterparts, Ladenson said.
Several studies have linked an increase in caffeine consumption with a higher risk of miscarriage among pregnant women. The US Food and Drug Administration has specifically advised pregnant women to avoid or limit their intake of caffeine.
Current tests to detect caffeine use sophisticated laboratory methods, including spectroscopy and chromatography. While caffeine-specific antibodies are commercially available, these antibodies are destroyed at high temperatures, like those of hot beverages, and consequently are not practical for use in home tests, the scientists say.
To develop the new immunoassay test, Ladenson and his associates obtained an antibody derived from the blood of llamas. The antibody is resistant to high temperatures due to its unusually stable structure.
They obtained the antibodies by repeatedly injecting the animals with caffeine to illicit an immune response to the drug. The researchers then cloned the caffeine-specific antibody and combined it with other chemicals to facilitate caffeine detection.
In early laboratory studies, the antibody mixture was used to measure the presence of caffeine in both caffeinated and decaf versions of coffee and cola. In general, the researchers found that test results were comparable to those of conventional chromatography tests and that the caffeine content of these beverages was accurately labeled.
The antibodies worked equally well in both hot and cold beverages and did not appear to show any false readings caused by structures that are similar to caffeine, Ladenson says. He has filed patents related to the research.
The study will appear in the 1 June edition of the American Chemical Societys Analytical Chemistry.